Method of treating suspensions of fibres to form aggregates



April 14, 1970 G. JACQUELIN 3,506,536

METHOD OF TREATING SUSPENSION-3 01 FIBRES TO FORM AGGREGATES Filed June13, 1966 2 Sheets-Sheet 1 FIG. 1

April 14, 1970 G. JACQUELIN 3,506,536

METHOD'OF TREATING SUSPENSIONS OF FIBRES TO FORM AGGREGATES Filed June13, 1966 2 Sheets-Sheet 2 l l l l l I 40} l l I l l l l United StatesPatent US. Cl. 162-1 13 Claims ABSTRACT OF THE DISCLOSURE A method oftreating a suspension of fibres to form aggregates which comprisessubjecting a suspension of the fibres in a liquid to rotationalagitation to establish a speed gradient between points in the suspensioncausing the formation of eddys, which result in the fibres movingtogether into groups. The grouped fibres cling to one another to formaggregates, the concentration by weight of the fibres in the suspensionat the beginning of the treatment being relatively low.

This application is a continuation-in-part of my earlier applicationSer. No. 427,040 filed Jan. 21, 1965 and now abandoned.

The present invention relates to a method of treating suspensions ofnatural, regenerated or synthetic fibres in a liquid medium.

The purpose of the method of the invention is to enable the formationwithin a suspension of aggregates of regular fibres which areindividualized and relatively consistent, said aggregates generallybeingof regular shape such as, for example, spheroidal, and of a size whichmay be of the order of the length of the fibres insuspension (0.2 to 15mm).

It is an object of the invention to provide amethod of treatingsuspensions of fibres comprising causing a general agitation in a liquidbath containing fibres in suspension, said agitation being carried outunder con ditions which are produced by the rotating and circulatingmovements of the said fibres in a weak shearing or cutting field so thatsaid fibres cling to one another and form aggregates, which are roughlygrouped or sized and of regular shape.

According to a' feature of the invention, the agitation of the bath isfollowed by filtration enabling the aggregates of the liquid medium tobe separated from the nonfibrous elements and if desired from thenon-aggregated fibres.

In this way, the fibres of the other solid components of a bath may beseparated, this being particularly advantageous and especiallyapplicable to the shearing of a paper pulp. At least two categories offibres may be separated, thus providing for manufacturing from the samesuspension at least two paper pulps having different properties. To thisend, the aggregates separated by filtration are disintegrated andreturned to homogeneous suspension by agitation in a liquid medium whilethe other components are removed with a filter and subjected to furthertreatment as desired.

The fibrous aggregates separated by filtration can also be drained andthen dried in a current of hot air, which technique has the advantage ofbeing more economical than the technique, Which is currently used, ofdraining and drying the paper pulp in sheets. Moreover, by thistechnique, independent aggregates are obtained, which are roughlygrouped or sized, light, easy to stock, and

readily manipulated and treated, and Which may be used for manypurposes.

According to another feature of the invention, the fibrous aggregatescan be agglomerated either by using the other components of the bath asbonds, or after impregnation with a deposited bond, said operation beingfollowed by a drying of the porous agglomerate thus obtained, and ifdesired also by a thermal treatment. Such agglomerates thus produced canbe used, depending upon the nature and amount of the bonds, as liningsfor walls, floors or other partitions, or for thermal or soundinsulation.

According to another feature of the invention, the fibrous aggregatescan be impregnated with a resin or with a prepolymer in order toconstitute fibrous granules for compression by heat in order to formmolded or laminated parts. In this way, a fibrous structure forminga'reinforcement can be given to molded or laminated parts by heat andunder pressure.

The invention also has as an object the provision of apparatus forcarrying out the aforesaid method, such apparatus comprising a tankwhich is to be partially filled from the bath to be treated, and meansfor gently agitating said bath.

The agitation means may comprise means for rotating the tank which maybecylindrical and mounted so as to rotate about an axis, or by a rotatablemember arranged in a fixed tank, or by at least one gas injectingmember.

The apparatus may be cyclically or continuously operated. In the lattercase, the apparatus may comprise a tank mounted on a horizontal axis andin which an Archimedean screw is arranged, the latter constituting theagitation means, if desired.

The invention also relates to the new industrial products obtained bycarrying out the method and which may be constituted by:

fibrous spheroids, the diameter of which may vary from 0.2 to 15 mm. andwhich may have a low apparent density of between 0.05 and 0.70, afterdraining and drying,

the sheared paper pulp,

a porous conglomerate having an apparent density between 0.02 and 1according to the field of use,

molded or laminated parts having a fibrous structure made by compressionand thermal treatment of granules formed from' fibrous spheroidsimpregnated with a resin or other products.

Various other features of the invention will become apparent from thedetailed description which is to follow, taken in conjunction with theaccompanying drawings which show various embodiments of apparatusaccording to the invention, by way of example, and in which:

FIGURE 1 diagrammatically illustrates cyclically-operated apparatusemployed in accordance with a first embodiment of the invention; 7

FIGURE 2 diagrammatically illustrates cyclically-operated apparatusemployed in accordance with a second embodiment of the invention; 1

FIGURE 3 diagrammatically illustrates cyclically-operated apparatusemployed in accordance with a third em-- bodiment of the invention;FIGURE .4 is a diagrammatic view illustrating a continuously operatedapparatus;

FIGURE 5 shows the paths and speed distributions of. the fibres in'thesuspension produced in the above apparatus; and

FIGURE 6 shows the variations in production and yield of the particlesas a function of the concentration of the fibres in the suspension.

According to the invention, a fibrous suspension to be 3 treated issubjected to agitation produced under conditions which cause:

(1) Rotating movements of the fibres enabling them to be hooked whenthey come into contact, either with each other, or with aggregates inthe course of formation, independent fibrous assemblies, relativelyconsistent, being developed by the addition of fibres to one another.

(2) A circulation in the mass of the suspension, so that a large numberof fibres and aggregates in the course of formation passes into adjacentareas having solid surfaces, where the shearing or cutting power,depending on the speed gradients of the fluid, causes the rotation ofthe fibrous elements and the formation of eddies in the fluidpropagating the above mentioned phenomenon. Moreover, the agitation ofthe suspension must be less turbulent for the sole reason that theshearing or cutting power caused by the relative movements of thesuspension and of the solid surfaces is sufiiciently low so as not todestroy the fibrous aggregates formed in the suspension. Moreover, thesurface of the solids in contact with the suspension is preferablysmooth and less adherent to the fibres so that they do not cling to themnor destroy the aggregates in the course of their movement. When theseconditions are combined, the changes in the structure of the suspensionsalso depend on the morphological and physiochemical properties of thefibres. Thus, certain fibres refuse to cling together and others, on thecontrary, rapidly form regular? aggregates. This aptitude of the fibresmay moreover be modified by physical or chemical treatments and by theaction upon them by the properties of the suspension medium.

In the case of paper fibres of substantiall similar length, if the axisof the rotation torques applied to the fibres by reason of the agitationof the suspension does not have a mandatory direction, the aggregatesappear in the form of separate regular pellets which are of relativelyuniform dimensions which may be of the order of the mean length of thefibres. They are easy to separate by means of a rough filtration and mayrepresent more than 80% of the total quantity of fibres. The dimensionsof said spherical pellets depend not only on the sizes of the fibres,but also on their concentration and the characteristics of the agitation(form and strength).

Thus, the invention enables a new industrial product to be manufacturedwhich is constituted by fibrous spheroids, the diameter of which mayvary from 0.2 mm. to mm. After draining and drying, they have a lowapparent density of between 0.05 and 0.70.

The drainability of the suspension of fibrous aggregates (aftertreatment) is clearly improved compared with that of the initialhomogenous suspension. Moreover, according to an importantcharacteristic phase of the method, the drying of the drained fibrouspulp (in the form of independent aggregates) may be effected in acurrent of hot' gas according to well known methods which could not bevapplied, up to the present, directly to paper pulp, which, in fact, hadto be drained in sheets (or layers) and dried in this state or evenbroken into pieces before drying. It will be apparent that the drying ofthe pulp directly obtained in the form of small and very permeableaggregates, in a current of hot gas, is much more economical andadvantageous.

The method of the invention also enables the fibres of the otherelements in suspension (fillers, fine elements, vessels and accessoryelements of annual plants in particular) to be separated. Thesenon-fibrous elements are incorporated very slightly with the aggregatesand conse-,

quently the majority remains in suspension. They may thus be easilyseparated by a rough filtration retaining the aggregates. Moreover,certain fibrous elements, the properties (strength, surface condition,length) of which do not allow their linking to other fibres, are alsoseparable from the rest of the other fibres, by means of this method.This is, for example, of use for modifying the properties of a paperpulp.

In order to shear a paper pulp, according to a particularly advantageousway of carrying out the method, the aggregates or fibrous spheroids areseparated by filtration, then they are disintegrated and replaced inhomogeneous suspension by agitation in a liquid medium of suitablenature and strength, the invention extending to the new industrialproduct constituted by the paper pulp thus sheared.

According to another way of carrying out the method of the invention,the fibrous spheroids formed in the bath may be agglomerated togethereither in their humid state, the non-aggregated elements of thesuspension, if desired, serving as a bond or a bonding agent, or afterimpregnation by a bond. Moreover, at the beginning of the treatment, thebath may contain deposited matter, serving particularly as a bond suchas, for example resins, gums, polymerizable or cross-linkable productsthis matter. being adapted for being put into solution or emulsion inorder to be integrated in the fibrous aggregates during their formationand/ or to be connected to the aggregates formed. A new industrialproduct is thus obtained, after drying and, if desired, thermaltreatment, said product being constituted by a conglomerate, which ismore or less porous, the apparent density of which may be still lowerthan that of the spheroids. It varies for example between 0.02 and 1.These spherules, associated or not With other matter, polymeric bondsfor example, enable panels and other products to be produced, theproperties of which may be varied to a large extent from the point ofview of density, strength, porosity, and thermal or sound insulation.

In another embodiment of apparatus for carrying out the method of theinvention, the fibrous spheroids, formed and dried, may be impregnatedwith a resin or with a prepolymer and may thus constitute fibrousgranules. By compression of said latter and thermal treatment if desiredor found necessary, molded or laminated parts may be produced, thefibres of which serve as a reinforcement. The inverntion thus alsopovides new industrial semi-finished products constituted by thegranules and the new industrial finished product formed by parts havinga fibrous structure.

Apparatus for carrying out the method can be cyclically (FIGURES 1 to 3)or continuously (FIGURE 4) operated.

In the case of the apparatus of FIGURES 1 to 3, the equipment comprisesa tank 1 containing the bath, i.e. the liquid, to be treated, whichpreferably only partially fills the said tank. This bath has in thesecircumstances a free surface 2 and is in contact with solid surfacesconstituted by the internal Wall of the tank and possibly by internalrigid elements. These solid surfaces may advantageously be smooth, i.e.without roughness, and their structure must be evolutive, i.e. withoutany abrupt variation of curvature, in order to prevent the fibreslinking 0r hooking together and violent shocks on the aggregates insuspension.

The relative movemet of the suspension and of the solid surfaces causingthe agitation necessary for carrying out the method is produced eitherby the movement of the tank itself (FIGURES 1 and 2) or by the movementof a member 3 internally located (FIGURE 3) or by the application ofother forces (for example, by injecting gas) or by various combminationsof these means.

In a particularly advantageous embodiment, the tank 1 is cylindrical andthe agitation is produced by rotating the member provided for agitatingthe bath preferably about the axis of the member, namely either the tank1 itself (FIGURES l and 2) or the rotatable member 3 (FIGURE 3). Theaxis of the tank may be horizontal (FIGURE 1), inclined (FIGURE 2) orvertical (FIG- URE 3).

This arrangement enables a suitable circulation of the fibres to beobtained and a sufficient speed gradient on the walls to be maintainedin order to produce the rotation of said fibres in different planes bycompounding the action of gravity and the action of rotation.

In the embodiment illustrated in FIGURE 3, the rotatable member 3 has ahighly developed movable surface which is, for example, a simple spiral.It could also have other shapes.

Whatever the embodiment envisaged (FIGURES 1, 2 and 3) may be, thecyclically operated apparatus is associated with means for filling andemptying the tank 1, put into operation at the beginning and end of thetreatment.

The continuously operated apparatus comprises a tank 1 and agitationmeans set up and adapted to operate in such a way that the circulationof the suspension is orientated to effect a continuous progression ofthe suspension from the inlet to the outlet of the tank where permanentfilling and emptying means are put into operation.

In the embodiment shown in FIGURE 4-, the tank 1 is cylindrical and anArchimedean screw 4 is arranged therewithin along its substantiallyhorizontal axis. This screw can moreover constitute the agitation means.

The tank 1 may be rotatable and the screw 4 fixed, or the tank may befixed and the screw rotatable, or the screw and the tank can even besecured and rotatable together.

In any case, the rotation of the agitation member (tank and/or screw)causes the progression of the suspension from the inlet 5 of the tank 1to the outlet 6. The sus pension to be treated is continuously fed inthrough a coaxial supply pipe 7 in the inlet 5, is subjected to thetreatment during its progression through the tank 1, and the treatedsuspension flows out through an emptying opening 8 to a utilizationcircuit 9 (for filtration and drying or agglomeration or diluting.etc.).

According to another embodiment, the continuous progressioh of the bathto be treated is eifected by the application of a difference in pressurebetween the inlet and outlet ends.

The paths and distributions of speed in the fibrous suspension subjectedto the above mentioned slight turbulent agitation, in the case where thetank 1 is cylindrical and is rotated in the direction of the arrow Fabout its horizontal axis is shown in FIG. 6-.

The solid line 2. represents the shape of the surface which is free fromthe suspension during this rotation. The dotted lines 35 and 36 inparticular, show the shape in projection on a straight section of thecylinder of the orbits followed by the suspended particles which for themost part are generally constituted by the fibres. These orbits are notstable for various reasons (beatings due to the drive by the flat wallslimiting the ends of the cylindrical curve, variations in the dimensionsof the particles in the course of the aggregation, vibrations and soon), but the projection retains the general shape indicated in thedrawing.

Tests have shown that a fibre AB (which is shown considerably enlargedin order to facilitate understanding and which is assumed to be in theplane of the cross section) has at its ends linear speeds VA and VBwhich are different at any given instant, on account of the shape of theorbits imposed by the shape of the tank and its movement and on accountof the sliding of the layers of fluid due to the inertia of thesuspension in the course of its drive under the action of the walls.

The gradient of speed thus existing between the diiferent layers offluid causes a shearing in the center of the suspension and produces atorque determining the rotation of the fibres. Moreover, the speed VRapplied to the center of gravity of the rotating fibre AB in questioncauses the circulation of this fibre along the indicated orbits.

The force M at point C communicated to the suspension by the movement ofthe wall of the tank is vectored with the action of gravity P at thesame point and deter- 6 mines the shape of the orbit followed by thefibres as shown by the resultant R.

In the course of these rotational and circulatory movements in ashearing field, movements which undergo ac celerations (positive ornegative) mainly in the areas C and D, there occur shocks between thefibres if the concentration is sufficient and consequently these fibrescling together.

Apart from this experimental illustration of the method of theinvention, the present invention has as an object the increasing of theefficiency of the treatment, and improving the output of the productsobtained and of varying these latter and their applications.

In accordance with the invention, the concentration by weight of thefibres in the suspension, at the beginning of the treatment is, lowerthan 15%. In the case of conventional papermaking fibres, this originalconcentration is preferably between one and four percent. In connectionwith leafy wood fibers (i.e. fibres from leafy European type trees), theproduction of aggregates is maximum, based on equal durations oftreatment and if the composition is not modified in the course oftreatment, when the original concentration of fibres is between 2.8 and3.4%.

According to another feature, the concentration of the fibres may bemodified during the treatment. Similarly, the composition of the fibroussuspension may be modified during this treatment. Moreover, a pluralityof successive additions of fibres having different qualities andproperties, may be provided during the same treatment.

Further features of the invention relate to modifications in the methodconsisting of Well determined aims in incorporating the additionalproducts either in the suspension itself or on or in the aggregates,whether the latter be simply drained or dried. In any case, theseparticular features will be clearly understood from the detaileddescription which follows.

It is specified above that the fibrous suspension must remainsutficiently fluid in order to permit the fibres to move with respect toone another in order to be organized into aggregate form under theaction of liquid currents.

In order that the fibres have a sufficient degree of freedom, theirconcentration in the liquid must remain relatively low. The mosteffective zone of concentration at the beginning of the treatment forthe conventional paper-making fibres, as stated above, is between 1 and4% by weight with respect to the fluid.

For leafy wood fibres treated for ten hours in a rotating cylindricaltank whose axis is inclined by about 45 with respect to the vertical,the peripheral speed of this tank being 35 meters per minute for adiameter of 20 cm., the variations in the production and the yield ofthe particles as a function of the concentration of the fibres in thesuspension are given by the curves illustrated in FIG- URE 6.

In this figure, the x axis shows the percentage concentration (C%) whichis equal to the ratio of the weight of the fibres placed originally inthe suspension and of the weight of the fluid of this suspension; thesolid line of the y axis shown the production (Pr) of the particlesformed in four liters of suspension, this production being expressed ingrams; the dotted line of the y axis shows the yield (R%) of thetreatment which is equal to the ratio of the weight of the particlesformed and of the total weight of the fibres placed originally insuspension.

The solid line curve 37 represents the variation in the production Prand shows that this production is maximum, for a fixed duration oftreatment and if the composition is not modified during this treatmentwhen the concentration C% is between 2.8 and 3.4%. The dotted curve 38shows the variation in the yield R% and shows that this yield ismaximum, under the same conditions as previously, when the concentrationC% is between 2.4 and 2.8%. Of course, for other natural or syntheticfibres, the optimum concentrations may be higher. They depend upon thelength and the suppleness of the fibres. Moreover, if new fibres areadded during the development of the aggregate, the optimum concentrationmay be moved towards denser zones. In any case, the profitable zones ofconcentration generally remain lower than 15%.

Thus, the concentration of the fibres may be modified during thetreatment. Several successive additions of fibres of different qualitiesand properties may even be provided during the same treatment, for theparticular purpose of obtaining a stratification.

Moreover, the fibrous suspension may comprise not only a fluid andfibres but also other products responding to the well-determined aimswhich are mentioned hereinafter. In any case, the composition of thisfibrous suspension may be established once and for all at the beginningof the treatment, may be also maintained constant during this treatment,or may even be modified in the course of said treatment.

It is important to note that the particles obtained, whether they beconstituted by simple aggregation without any binding agent or whetherthey are mixed or covered with other products, have a structure which issubstantially isotropic, i.e. Without any preferential orientation ofthe fibres. This property has particular interest in all theapplications envisaged in the following.

In order to favor the formation and development of the fibrousaggregates, germs or primers are introduced into the suspension at thebeginning of the treatment. The latter may be constituted by mineral ororganic powders, crystals, particles of natural or synthetic resins,sawdust, particles of cork or bark, fibrous agglomerates which may ormay not be manufactured for this purpose during a previous operation orproduced by the disintegration of paper-making pulp or old papers,disintegrated cardboard or the like.

In order to favor the agglomeration of the fibres, gaseous bubbles maybe diffused in the center of the suspension.

The composition of the fibrous suspension treated for the purpose ofgranulation may be very complex. Concerning the fibres, they may varyconsiderably in dimension, shape and nature and utilized alone or in amixture (mineral fibres; asbestos, glass, drawn rock, drawn metals;various natural, regenerated or synthetic fibres which are or are notchemically modified, and so on). Apart from these fibres, additionalproducts may be introduced into the fluid which are intended either forfacilitating or controlling the particulation, or for conferring to theparticles particular properties which will substantially be useful.

Concerning the additional products intended to facilitate or control theparticulation, one may use the above mentioned primers, flocculatingagents, dispersing agents, moisturizing agents or others, products insolution or in suspension which are precipitable or not during thetreatment, such as latex for example, agents modifying the physical orchemical properties of the liquid medium viscosity, pH, etc. ormodifying the superficial or internal properties of the fibres and otherelements in suspension.

Concerning the products intended to give particular properties to thegranules for later use, products in solution, emulsion, suspension,encapsulated products and the like may be incorporated in thesuspension, so that they become integrated by inclusion, adsorption,chemical contact, grafting, with the fibrous network of the aggregates.These products may be mineral or organic charges, adhesives, gum,polymers or prepolymers, natural or synthetic, thermoplastics orhardenable resins, various monomers, polymerizable or cross-linkablecondensable products.

The fluid which is generally utilized for placing the fibres insuspension is generally water. But it is obvious that other pure ormixed liquids may be used. In particular, the fluid may be entirelyconstituted by polymerizable, condensable or cross-linkable products.

Cir

Reactions may also be provoked either in the medium where the particlesare located or in the particles after draining one part of the liquidmedium which surrounds them, or even after drying the particles.Moreover, these latter may be treated in the vapor phase bypolymerizable, condensable or cross-linkable products. They may also becovered by a simple projection of various products such as thosementioned above. In any case, the reactions may be triggered by anyconventional means such as catalysis, irradiation and so on, possiblypermitting graftings on the elements constituting the particles.

Moreover, in order to obtain particles which are expanded in part,porophores or inflating agents may be included, for the purpose ofdeveloping small bubbles, forming foam. This expansion of the alveolarproduct thus obtained may be caused either during the manufacture of theparticles or granules, or only at the moment when they are used duringlater operations, and this expansion may affect all or only part of saidparticles or granules.

The result is that numerous modifications of the method can be carriedout. They may be carried out separately from one another or in variouscombinations and, consequently, a very wide range of varied products canbe obtained.

When the composition of the fibrous suspension is modified during theparticulation or granulation by new additions, the program of thedevelopment of the operations is established as a function of the aim tobe achieved and the product to be obtained. Thus, the particulation orgranulation may be begun with a composition comprising cheap raw fibres:mechanical pulp, pulp made from old papers, etc. and terminated with theaddition of different fibres which surround the granules by giving thema better appearance, (bleached or colored fibres) or properties whichare useful for later transformation of the particles or granules.Whatever is possible with the fibres is also possible with the productsaccompanying said fibres.

Two or more types of particles or granules can even be produced in whichare included products capable of reacting together finally whenparticles or granules of different types are close to one another bymeans of an external action: mechanical, physical or chemical,irradiation, catalysis, etc., for the sole purpose of producing the mostvaried effects: change of color, variations in size or mechanicalproperties, release of volatile products, etc.

Several examples are hereinafter given in a non-limiting manner toillustrate the method of the invention:

EXAMPLE 1 For treating a suspension in water of blanched beech fibreshaving a concentration of 3%, treatment is effected under the followingconditions: the tank (FIGURE 2) is made of polyvinyl chloride and isrotated about its axis, which is inclined at 45. The ratio of the diam-.eter of the cylinder to its height is about 1. The peripheral speed ofthe cylindrical wall is 40 meters per minute. After five hours oftreatment, almost all the fibres of the suspension are separated intosmall regular pellets with a diameter of about 1 mm.

EXAMPLE 2 There is treated, under the same conditions as in Example 1, asuspension of resinous fibres. Fibrous pellets are then obtained, thediameter of which is about 3 EXAMPLE 3 For treating a suspension ofspruce fibres (unbleached kraft pulp) at a concentration of 1.5%, theapparatus diagrammatically illustrated in FIGURE 1 is rotated about itsaxis at a peripheral linear speed of 30 meters per minute. After severalhours of agitation, fibrous pellets .9. with a diameter of about mm. areseparated from the suspension.

EmMPLE-4 For the production of a very porous conglomerate, thesuspension of 'beech pellets obtained in Example 1 is poured onto arough sieve. The cake of pellets thus obtained is dried after beingdrained. The fine elements andthe fibres, whichremain in suspension,serve as bonds between the spheroids and thus" a very lightporousagglomerate is obtained, having a density of about 0.14.

EXAMPLE'G For the production of a very resistant agglomerate, thesuspension of pellets obtained in Examplel is drained and replaced insuspension without destroying the pellets, in a water/ alcohol solutionof a resorcinol-fonmol precondensate. After agitation, drainage anddrying, and a slight thermal treatment (15 minutes at 110 C.), a

very rigid agglomerate is obtained with a good porosity and goodmachinability.

EXAMPLE 7 If it is required to produce colored fibrous granules intendedto be associated with a larger quantity of bleached granules in order tomanufacture a decorative covering, granulation is begun with an aqueoussuspension containing 2% by weight of raw resinous paper-making fibresproduced by a highly effective baking. After the granules have beenformed according to the previously described method, colored fibres areadded with respect to the weight of the initial fibres. The treatment isfollowed until the granules are suitably covered by raw fibres. Thus,the granules with a diameter of 6 to 8 mm. are obtained having thecoloring of the fibres which were added last.

EDLAMPLE 8 In this example, the requirement is to produce very cheapsupple granules for manufacturing sub-layers for covering the ground.The fibres utilized are constituted by mechanical resinous pulp(paper-making pulp constituted by rasped wood); moreover, fragments ofdisintegrated old paper are added in an amount of and fine sawdust in anamount of 10%. In order to facilitate the granulation, 10%, with respectto the weight of the fibres, is added of a less stable styrene-butadienelatex whose flocculation will be produced during the granulationtreatment.

After treatment of a few hours, granules are obtained with aheterogeneous granulometry or grain size, from about 1 mm. to 8 mm.

After draining and slight drying, these granules constitute a light rawmaterial, of apparent density between 0.10 and 0.30, which is supple andeconomical for the manufacture of agglomerates.

EXAMPLE 9 For manufacturing granules covered with fibres of coloredrayon for the purpose of constituting a decorati-ve coating Stratifiedunder high pressure, after impregnation with transparent, thermosettingresins, particula- For manufacturing granules of fibres of polyvinylchloride, for the purpose of constituting insulating supple:agglomerates, polyvinyl chloride fibres of 2.5 denier and 3 mm. lengthare dispersed in water in an amount of 2%. After a few hours oftreatment, all the fibres are agglomerated in the form of granules whosediameter is about 5 to 6 mm. At this moment 20% of a latex which is madeinsoluble, on the granules, is added in order to facilitate their finalagglomeration.

EXAMPLE 11 For manufacturing particles or granules containing athermoplastics polymer for the purpose of manufacturing parts forextrusion, and an aqueous suspension containing 2% of fibres of a kraftpaper-making pulp and an equal weight of polyvinyl chloride in the formof fine powder, is treated. In order to facilitate the dispersion of thepowder, 0.02% of a tension-active agent is added. In order to increasethe fixing of the powder in the fibrous network, a flocculantpolyethylene-amine for example may be added.

After a few hours of treatment, the particles or granules are drainedand dried and can be used for supplying a machine for pressing toiletsoap into cylinders.

EXAMPLE 12 For the production of particles or granules intended formanufacturing molded parts such as packing cases, an aqueous suspensioncontaining 1% of mechanical pulp and 2% of a pulp of highly effectivebirch fibres is treated. A solution of soda alginate is added in anamount of 896 with respect to the fibres; when the adjuvent is welldistributed in the suspension, 5% of aluminum sulphate in solution isadded by fractions. There is created a precipitate of aluminum alginatewhich accelerates the formation of the fibrous granules and gives themafter drying an increase in cohesion and rigidity.

EXAMPLE 13 For manufacturing thermoplastics granules reinforced withfibres, for extrusion or molding purposes, a suspension of bleachedbeech paper-making fibres is produced in an amount of 2% in a monomer,methyl methacrylate for example. After forming the granules, the excessmonomer is separated and polymerization is effected by the separatedgranules, by a conventional means (atomization of a catalyst,irradiation, etc.). The granules may be kept on a rotating sieve inorder to limit their agglomeration. Thus reinforced granules containinga high proportion of polymer and suitable for manufacturing molded orextruded objects are thus obtained.

What is claimed is:

1. A method of treating a suspension of cellulosic fibres to formaggregates comprising subjecting a suspension of the fibres in a liquidin a cylindrical tank of a diameter of about 20 cm. to a gentlerotational agitation, with a pcripheral speed of the order of 35 metersper minute whereby a speed gradient is established between differentpoints in the suspension causing the formation of eddies, which resultin the fibres moving together into groups and becoming mechanicallyinterlocked, the grouped fibers being constituted so as to cling to oneanother to form aggregates under the above conditions, the concentrationby 11 Weight of the fibres in the suspension, at the beginning of thetreatment, being less than 15%. 1

2. A method according to claim 1 wherein the concentration of the fibresis modified during the treatment.

3. A method according to claim 1 wherein to improve the formation anddevelopment of fibre aggregates, seeds are introduced into thesuspension at the beginning of the treatment.

4. A method according to claim 1 comprising the further step offollowing the agitation of the bath by a filtration to separate theaggregates from the liquid medium and from the non-fibrous elements andany non-aggregated fibres present.

5. A method according to claim 4 comprising the further step ofdisintegrating the aggregates separated by filtration and replacing themin homogeneous suspension by agitation in a liquid medium to constitutea refined pulp.

6. A method according to claim 4 comprising the further step of drainingthe fibrous aggregates separated by filtration and then drying them in acurrent of warm gas.

7. A method according to claim 1, wherein the fibrous aggregates areagglomerated by bonding, and the porous conglomerate thus obtained isdried by thermal treatment.

8. A method according to claim 1 comprising the further step ofimpregnating the fibrous aggregates with a binder to constitute fibrousgranules compressed while hot to form a part.

9. A method according to claim 1, wherein said agitation is produced byrotating a tank containing the suspension.

10. A method according to claim 1, wherein filler products'controllingthe granulation of the fibrous aggregates and chemical products areintroduced into the suspension.

11. A method according to claim 10, wherein the composition of thefibrous suspension is modified during the treatment.

12. A method as claimed in claim 1 comprising impregnating the fibrousaggregates with a pre-polymer to constitute fibrous granules which arecompressible while hot, to form a body.

13. A method as claimed in claim 1, wherein said agitation is producedby injecting gas into the suspension.

References Cited UNITED STATES PATENTS 2,685,825 8/1954 Novak 16233,170,834 2/1965 Oesterheld 162-3 3,297,516 1/1967 Naumann 16233,421,975 1/1969 Woolery 1623 HOWARD R. CAINE, Primary Examiner US. Cl.X.R. 1623; 210-49

